1. Field of the Invention
This invention pertains to automatic devices for the control or regulation of engine speed. Such automatic devices are commonly referred to as "governors". More particularly, this invention pertains to governors for the automatic control of engine speed where the desired engine speed varies with time. The desired engine speed may vary either in a stepwise fashion or in a continuous manner as a function of time.
2. Description of the Prior Art
Simple mechanical governors that cause an engine to operate at a fixed speed are well known in the art. However, when a load is applied to an engine that is controlled by a simple mechanical governor, the speed or rate of rotation of the engine sags or decreases significantly below the no-load rpm. If the mechanical sensitivity of the governor to changes in rpm is increased in an attempt to reduce the sag in rpm with load, the engine and control mechanism tends to become unstable. Digital electronic control of engine speed allows the introduction of nonlinear processing techniques to obtain accurate control of engine rpm that exhibits little sag with load and at the same time also avoids engine instability. A digital electronic control system also can be used to vary the engine speed in a predetermined manner in response to varying demands on the engine.